How to adjust adjustable rockers?

OP, is this just 1 lifter tapping?

Step 1: Try the 1/4 or even 1/2 added turn. (But I'd skip to step 2 just to be sure things are set correctly.)

Step 2: If the clatter does not subside, then you'll need to go through the process of backing off, then snugging up each rocker, and then add the 3/4 to 1 full turn on the adjuster. Use the chart in post 2 to determine which rockers to adjust at what crank angle.

If you are not familiar with valve and crank positions in that chart: Each line of that chart is with the crank rotated 90 degrees CW from the prior setting. Line 1 is with the timing marks at 0 and the valves on cylinder #6 are 'at overlap'... i.e., both valves on #6 will be slightly open about equally. If not, then rotate the engine a full turn 'til the 0 marks line up again and the #6 valves will be at overlap and you can start the process.

Step 3: If that does not do it, then you'll have to investigate the possibililty of a lifter(s) getting weak/collapsing and needing to be replaced. That problem seems to be getting more common these days.